When you are getting down and dirty with your boo and when you're about to ejaculate; you call your parents just to say, "hello".
Ryan: "Hey, Adam! There's this chick that I met in Alabama over Spring Break last month that always tried to do the Home-Sweet-Home shit!"
Adam: "What the fuck is wrong with that bitch?"
When one feels home sick, i.e. misses one's home and lifestyle, in his/her own home due to the prolonged stay of uninvited guests. There is literally guests' stuff everywhere. Whatever they like is being cooked too. They practically never wanna leave.
You are in your own house, but not really. Life begins to suck.